Year 1 is where the majority of the effort occurs. And that largely depends upon whether you are planting crowns, or seedlings. (Seedlings are more work, since you'll plant them deep, but only fill in their trench a bit over a year or two. Crowns get planted and that's about it)

The rest is weeding and re-applying mulch, harvesting (after about year 3), and removing/destroying canes at the end of the season to remove habitat for things like asparagus beetle (at least around here)